DESCRIPTION

The erase and werase routines copy blanks to every
position in the window, clearing the screen.

The clear and wclear routines are like erase and
werase, but they also call clearok, so that the screen is
cleared completely on the next call to wrefresh for that window
and repainted from scratch.

The clrtobot and wclrtobot routines erase from the cursor to the
end of screen. That is, they erase all lines below the cursor in the window.
Also, the current line to the right of the cursor, inclusive, is erased.

The clrtoeol and wclrtoeol routines erase the current line
to the right of the cursor, inclusive, to the end of the current line.

Blanks created by erasure have the current background rendition (as set
by wbkgdset) merged into them.

RETURN VALUE

All routines return the integer OK on success and ERR on failure.
The SVr4.0 manual says "or a
non-negative integer if immedok is set", but this appears to be an error.

X/Open defines no error conditions.
In this implementation,
functions using a window pointer parameter return an error if it is null.

NOTES

Note that erase, werase, clear, wclear,
clrtobot, and clrtoeol may be macros.

PORTABILITY

These functions are described in the XSI Curses standard, Issue 4. The
standard specifies that they return ERR on failure, but specifies no
error conditions.

Some historic curses implementations had, as an undocumented feature, the
ability to do the equivalent of clearok(..., 1) by saying
touchwin(stdscr) or clear(stdscr). This will not work under
ncurses.

This implementation, and others such as Solaris,
sets the current position to 0,0 after erasing
via werase() and wclear().
That fact is not documented in other implementations,
and may not be true of implementations
which were not derived from SVr4 source.

Not obvious from the description,
most implementations clear the screen after wclear
even for a subwindow or derived window.
If you do not want to clear the screen during the next wrefresh,
use werase instead.